1. Field of the Invention
This invention relates generally to semiconductor manufacturing, and, more particularly, to a method and apparatus for improving performance of one or more parameters relating to a wafer process based upon error effects that transmit throughout a manufacturing system.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today's manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of important steps. These process steps are usually vital, and therefore, require a number of inputs that are generally fine-tuned to maintain proper manufacturing control.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final testing of the completed device, are so different from one another and specialized that the processes may be performed in different manufacturing locations that contain different control schemes.
Generally, a set of processing steps is performed across a group of semiconductor wafers, sometimes referred to as a lot. For example, a process layer that may be composed of a variety of different materials may be formed across a semiconductor wafer. Thereafter, a patterned layer of photoresist may be formed across the process layer using known photolithography techniques. Typically, an etch process is then performed across the process layer using the patterned layer of photoresist as a mask. This etching process results in the formation of various features or objects in the process layer. Such features may be used as, for example, a gate electrode structure for transistors. Many times, trench isolation structures are also formed across the substrate of the semiconductor wafer to isolate electrical areas across a semiconductor wafer. One example of an isolation structure that can be used is a shallow trench isolation (STI) structure.
The manufacturing tools within a semiconductor manufacturing facility typically communicate with a manufacturing framework or a network of processing modules. Each manufacturing tool is generally connected to an equipment interface. The equipment interface is connected to a machine interface to which a manufacturing network is connected, thereby facilitating communications between the manufacturing tool and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script, which can be a software program that automatically retrieves the data needed to execute a manufacturing process.
FIG. 1 illustrates a typical semiconductor wafer 105. The semiconductor wafer 105 typically includes a plurality of individual semiconductor die 103 arranged in a grid 150. Using known photolithography processes and equipment, a patterned layer of photoresist may be formed across one or more process layers that are to be patterned. As part of the photolithography process, an exposure process is typically performed by a stepper on approximately one to four die 103 locations at a time, depending on the specific photomask employed. The patterned photoresist layer can be used as a mask during etching processes, wet or dry, performed on the underlying layer or layers of material, e.g., a layer of polysilicon, metal or insulating material, to transfer the desired pattern to the underlying layer. The patterned layer of photoresist is comprised of a plurality of features, e.g., line-type features or opening-type features that are to be replicated in an underlying process layer.
Turning now to FIG. 2, a typical flow of processes performed on a semiconductor wafer 105 by a semiconductor manufacturing system is illustrated. A manufacturing system processes semiconductor wafers 105 by initiating a sequence of processes that are to be performed on a batch of semiconductor wafers 105 (block 210). The manufacturing system may then acquire and analyze metrology data relating to the processed semiconductor wafers 105 (blocks 220, 230).
Based on the analysis of the metrology data, the manufacturing system may determine whether there are further process steps to be performed on the semiconductor wafers 105 (block 240). Upon a determination that there are no further process steps to be performed on the semiconductor wafers 105, the manufacturing system stops processing the wafers 105 (block 250). Upon a determination that additional process steps are to be performed on the wafers 105, the manufacturing system may calculate adjustments to be made to the subsequent process based upon the metrology data analysis (block 260). The manufacturing system then performs the modified process to correct or compensate for errors discovered during the analysis of the metrology data (block 270).
Among the problems associated with the current methodology include the fact that there may be a finite amount of uncertainty relating to the accuracy of one or more process steps that are performed on the wafers 105. Often, these uncertainties can accumulate, causing a cumulative error factor on the processed wafers 105. Additionally, these uncertainties in the process steps may cause an uncertainty in the finished wafers 105. Therefore, one or more end-of-line parameter(s) may have an inherent amount of uncertainty, thereby reducing confidence that the devices manufactured from the processed wafers 105 will operate properly.
Additionally, due to the uncertainty that may exist in certain processes, along with the uncertainty of the end-of-line parameters, controlling the process through modeling is more difficult. Therefore, the uncertainty relating to various portions of the manufacturing system may result in processed semiconductor wafers 105 of reduced quality.
The present invention is directed to overcoming, or at least reducing, the effects of, one or more of the problems set forth above.